solar system vocabulary

Asteroid

an irregularly shaped rock that orbits the Sun.

Comet

a space object made of ice and dust that orbits a star and develops a long, bright tail as it nears its star.

Core

the center of an object.

Crater

a hole in the ground caused by the impact of an object from space.

Dwarf planet

a nearly round object that orbits a star, is smaller than a planet, and is not a satellite of another object.

Gas giant

a large planet that is mainly made up of gases.

Gravity

the force that pulls all objects toward each other.

Moon

a huge ball of rock that travels around a planet; a natural satellite.

Orbit

to revolve around another object.

Planet

large bodies, natural satellites, that orbit the Sun, a star.

Satellite

a natural or human-made object that orbits Earth or another object in space.

Solar system 

a group of objects in space that orbit a star.

Star

a body in outer space, made of hot gases, that shines in the night sky.

Terrestrial

like Earth; describes planets that are rocky and Earthlike in size.

Asteroid belt

the area in space between Mars and Jupiter where most asteroids orbit.

Atmosphere

a layer of gases surrounding a planet, star, or moon.

Gas

a substance with no fixed volume or shape that can expand freely.

Helium

the second lightest chemical element; often a gas.

Hydrogen 

the lightest chemical element; often a gas.

Mass

the measure of the amount of matter in an object.

Methane 

a colorless, odorless, flammable gas commonly called "natural gas".

Oxygen

a gas that has no color, taste, or smell, and which people need to live.